The present invention relates generally to GPS position determination, and more particularly to GPS ambiguity estimation and verification.
Global Positioning System (GPS) satellites transmit signals that can be processed to determine position. In general, GPS satellites transmit signals including information relating to time of transmission and position of transmission, with the signals being transmitted about two different frequencies. Use of the information by a receiver allows the receiver to determine a pseudo range measurement to the transmitting satellite.
More precise range measurements may be derived by tracking phase of the signals received by the receiver. Measurement of phase, however, may provide ambiguous results. The ambiguities may be estimated, with the estimated ambiguities used in providing relatively precise position information for the receiver.
Unfortunately, the estimated ambiguities may be incorrect, and they may be incorrect by an amount that is greater than may be allowed for some applications.